The present invention concerns means for enhancing the X-radiation-inhibiting capability of electrical feed-through receptacles in the envelopes of television cathode ray picture tubes. It is especially concerned with such inhibiting in relation to the high-voltage anode button of such tubes.
X-radiation is generated internally incidental to tube operation and is rendered completely innocuous in television picture tubes by the shielding provided in the composition of the glass of the tube envelope. The radiation that passes through the glass of standard television cathode ray tubes normally is less than 0.05 milliroentgen/hour, which is equivalent to the average normal background radiation of the environment.
In order to bring high voltage into the interior of a picture tube, the tube envelope must be penetrated by a high voltage lead or conductor. The high voltage lead is commonly brought through the envelope by means of a high voltage receptacle or "anode button". Because the shielding intergrity of the envelope is broken at this point of high voltage transgression, special precautions may be required to assure that the X-radiation shielding effected by the anode button is adequate under all operating conditions of the tube.
Prior art means for enhancing the inhibition of X-radiation from anode buttons and other high-voltage feed-through receptacles have comprised, for example, metallic shields enclosing the area of electrical interconnection, and usually embodied in an insulative anode "cap" which forms a protective arc-suppressing enclosure when the high voltage interconnection to the receptacle is made.
Certain cathode ray picture tubes of special design, such as the post-deflection focus type tube, require the introduction of more than one high potential into the envelope of the picture tube. This potential is commonly supplied by means of a feed-through receptacle similar to the anode button, and located near or in the flange area of the faceplate. The X-radiation-inhibiting characteristics of receptacles of this type can also be enhanced by the means according to the present invention.